Secondary curing is a common manufacturing process used to bond composite parts. The laminates (substrates) are first fabricated and then bonded together using an adhesive with the use of a high pressure high temperature autoclave. FIG. 1 shows a typical sequence for the fabrication of a composite bonded part using an autoclave which includes the steps of the fabrication of the laminates, the first cure cycle, the bonding of the laminates, the secondary cure cycle and finishing with the bonded part. FIG. 2 shows the configuration of a substrate, adhesive and scrim prior to being bonded together using an autoclave. FIG. 3 shows a commercially available scrim used in composite bonding.
Though adhesively bonded parts exhibit many advantages such as lighter weight over mechanically fastened parts, the autoclave process is expensive and causes degradation of the mechanical properties and shape of the laminates. When laminates such as carbon fiber laminates are re-heated during secondary curing, their mechanical properties can be degraded and also the process requires molds and tools to prevent deformation of the original shape of the part which adds additional cost and time to the overall process. Moreover, after the part is bonded, there is the potential of internal stress cracks resulting from thermal stresses created during the bonding process.